1. Field of the Invention
The present invention relates to a mobile communication system, which allows multiple subscriber identity codes to a single terminal device to represent the single terminal device, the multiple subscriber identity codes including a (first) subscriber identity code such as a telephone number corresponding to a (first) telecommunications carrier providing a primary contract and another (second) subscriber identity code corresponding to another (second) telecommunications carrier. The present invention also relates to a subscriber identity code notification apparatus applied to the mobile communication system.
2. Description of the Related Art
There has been a widely used service whereby multiple telephone numbers are assigned to a single mobile information terminal device such as a mobile telephone, so that its subscriber is able to selectively use the telephone numbers depending on his or her intended use.
In such a service, generally, not only a telephone number assigned to the terminal device according to the primary contract with a telecommunications carrier but also another telephone number are assigned by the same telecommunications carrier according to the accessorial service in relation to the primary contract. This allows a user to selectively use the telephone numbers in an appropriate manner.
In recent years, however, another type of service has already started such that different telecommunications carries assign multiple telephone numbers to a terminal device that functions for a single line at the same time.
In such a case, since considerations are made so that a user (subscriber) is able to continuously use the existing terminal device (mobile telephone) as before, the user is able to use the service without the need of buying a dedicated terminal device
It is to be noted that when the existing terminal device is used, subscriber identity information stored in a Subscriber Identity Module (SIM) card applied to the terminal device, namely only a single subscriber identity code (telephone number) can be displayed on an indicator, in response to a specific key operation on the terminal device.
This is because a circuit in the existing terminal device is configured to display only a single subscriber identity code, namely telephone number. Even if multiple subscriber identity codes are made to store in a SIM card, it is impossible to display multiple subscriber identity codes as far as the above circuit configuration is employed.
In connection with the service that makes multiple subscriber identity codes available on a single terminal device, there are several proposals.
JP H10-290294 A (hereinafter, referred to Patent Document 1) proposes a technique of allowing a user to use multiple telephone numbers, without the necessity of holding multiple telephone numbers in a mobile telephone.
Patent Document 1 discloses that an audio guidance is given for prompting a user to input the period of service, charged destination information, registration number, and secondary subscriber number, via a mobile switching center. In response to the guidance, information that has been input by the user beforehand is registered. In addition to the original subscriber number, another subscriber number is temporarily made available on an identical terminal device.
JP 2002-152793 A (hereinafter, referred to Patent Document 2) proposes a technique of permanently assigning multiple telephone numbers to a single terminal device without the need for registration of numbers on the terminal device.
Patent Document 2 discloses that an incoming or outgoing call is generated on the terminal device with a communication function for a single system and multiple subscriber numbers A and B for use in a single system. A base transceiver station establishes communication with the terminal device via a radio interface for a single system. A mobile communication system manages the incoming or outgoing call generated by the terminal device. If multiple subscriber numbers A and B are to be changed depending on the intended use or purpose, the mobile communication system is allowed to change between the multiple subscriber numbers depending on the intended use or purpose.
JP 2006-121335 A (hereinafter, referred to Patent Document 3) proposes that in a case where a terminal device for utilizing telephone communication based upon each of multiple telephone numbers, the terminal device is configured so that when a user receives an incoming call, the user is able to confirm which telephone number has received the incoming call.
Patent Document 3 discloses that multiple telephone numbers are read out of a Universal Subscriber Identity Module (USIM) by means of the controller of the terminal device. The radio communication section is controlled to send the telephone number to the communication management system on a mobile telephone communication network so as to authenticate each telephone number for communication. Then, upon receipt of an incoming call for the telephone number that has been authenticated, the controller controls the speaker or display section to output the information that specifies the telephone number together with the notification of the incoming call.
JP 2002-305580 A (hereinafter, referred to Patent Document 4) proposes the purpose of automatically updating the telephone directory data retained by the receiving-side terminal device that has received the notification that the telephone number has been changed. Then, the transmitting-side terminal device is notified of the update.
According to the technique disclosed in Patent Document 4, the above notification is made by a character message or the like. Therefore, the telephone number that has been assigned to the above transmitting-side terminal device can be checked with eyes on the transmitting-side terminal device that has transmitted the changed telephone number.
In any one of the proposed techniques, multiple identity codes cannot be displayed on the terminal device without performing a process for adding a specific circuit to the terminal device.
Accordingly, the subscriber (user) of the terminal device has to record an identity code separately beforehand in a note or the like at the time of learning the identity code, such as at the time of a contract or registration, in order to tell a third party a part or the entire of multiple identity codes registered to be available.
It should be appreciated that even if multiple identity codes are registered to be selectively available according to the situation as described above, such a cumbersome procedure for daily use is not eliminated. This will remain a concern for insufficient utilization.
Besides, when a specific switch or the like for displaying multiple identity codes on the terminal device is not provided, or when a specific operation is not required even for an existing key as a precondition, an appropriate procedure is needed for displaying the identity codes based upon what action should be a trigger.
It is to be understood that any one of the above Patent Documents lacks a viewpoint of the trigger for displaying the identity codes. It is also to be understood that that suitable measures are not suggested.